Baylis–Hillman Bromides as a Source of 1,3-Dipoles: Sterically Directed Synthesis of Oxindole-Fused Spirooxirane and Spirodihydrofuran Frameworks



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Poles apart: The sterically directed [3+2] cycloaddition reactions of dipoles that were generated from Baylis–Hillman bromides with isatin dipolarophiles provided a facile synthetic route to spirodihydrofuran oxindoles and spiroepoxy oxindoles (see scheme). a)–c) Me2S, Cs2CO3, DMF, 15–20 °C, N2, 8 h. EWG: a) CO2Me (Z), b) CO2Me, and c) CN (E).